Camera shutter mechanism

ABSTRACT

There is provided herewith an improved photographic camera having an objective lens with a constant diaphragm aperture. A shutter mechanism comprises a single main shutter blade movable back and forth by an opening and closing impulse over the diaphragm aperture. In conjunction with the main shutter blade there is a cover blade which moves in a plane parallel to the plane of movement of the main shutter blade, both sweeping over the diaphragm aperture. The cover blade is spring biased against the main shutter blade and follows the movement thereof.

United- States Patent Rentschler I [54] CAMERA SHUTTER MECHANISM [72]inventor: Waldemar T. Rentschler, Calmbach/Black Forest, Germany [73]Assignee: Prontor-Werk Alfred Gauthier, G.m'.b.H., Calmbach/Schwarzwald,

Germany 221 Filed; Nov. 27, 1970 [21] Appl. No.2 93,035,

30 Foreign Application Priority Data lllllllllllll FOREIGN PATENTS ORAPPLICATIONS Germany .....95/59 608,091 9/ 1960 0 PrimaryExaminer-Joseph F. Peters Attorney-March, Le Fever & Wyatt [s71 ABSTRACTThere is provided herewith an improved photographic I camera having anObjective lens with a constant diaphragm aperture. A shutter mechanismcomprises a single main shutter blade movable back and forth by anopening and closing impulse over'the diaphragm aperture. In conjunctionwith the main shutter blade there is a cover blade which moves in aplane parallel to the plane of movement of the main shutter blade,

both sweeping over the diaphragm aperture. The cover blade is springbiased against the main shutter blade and follows the movement thereof.

8 Claims, 20 Drawing Figures Italy ..95/59' Patented Aug. 29, 1972 4Sheets-Sheet 1 Hlll INVE N TOR Waldemar [Rentschler Arthur A.MarchATTORNEY Patented Aug. 29, 1972 4 Sheets-Sheet 2 INVE N TOR WaldemarIRentschler Arthur A. March ATTORNEY Patented Aug. 29, 1972 4Sheets-Sheet 5 L :INVE N TOR Waldemar T.Rentschler Arthur A. March ATTORNEY P tented Aug. 29, 1972 4 Sheets-Sheet .4.

IN VE N TOR Waldemar [Renfschler Arrh ur A. March A TTORNEY I CAMERASHUTTER MECHANISM blade movable back and forth across the shutteropening by an opening and closing drive mechanism. The effective shutteropening of the objective is preferably set into the area of 1:11, insome cases also in the area of 1:8, while the shutter opening has adiameter of about 5mm. Owing to the simple structure of these shutterstheir shortest exposure time usually is about 1/ 100 sec;

' at best l/200 sec.

, Cameras of the aforementioned type are essentially designed to servethe fair weather photography." of socalled snapshot amateurs. This groupof buyers accepts the disadvantage of a relatively restricted workingrange in return for a low purchase price. The limitations of the workingrange are established, on the one hand, by the fact that thephotographic activity must end as, a levelof illumination which is notyet really low, specifically at about 1,600 Apostilb this corresponds topairing aperture 8 at 1/30 sec and 18 DIN FE), while on the other hand,when films of medium sensitivity are used, at pairing of aperture 8 and1/ 100 sec over exposure of about two aperture levels may result whenthe illumination is intense.

If, in the-interest of an expanded photography range when lightintensity is low, the aperture of the objective is opened wider, which,on the basis of optical quality of many simple objectives, is possiblewithout trouble, the danger of excess exposure is increased.

On cameras with shutters with electronic exposure time setting as wellas an objective with fixed shutter 1:8 the working range does notactually end at aperture 8 and U30 sec, but here the limit of the timerange for photographs is out of hand, for which a dislocation in thedirection of lower light intensity would be desirable. Amateurphotographers desiring an enlarged working range of their cameras, cantherefore not use cameras of the above type, although the quality of thepictures in the working range of this camera are on a remarkably highlevel, both from the point of view of the quality of the objective aswell as the precision of the exposure time setting.

The basis of this invention is the development of cameras of the abovetype with but nominal additional expenditure in design and thus cost insuch a direction that an extension of its past working range isachieved. Such extension can be seen either in the employment ofobjectives with greater light intensity in order to prolong thereby thedaylight-photo-day for the camera user, but also in the reduction ortotal elimination of the danger of over-exposures. The second goal isalso important since it is true that black-and-white films haveconsiderable leeway in exposure and therefore are not overly sensitiveto excess exposures. On the other hand, color films are exposed withmuch more exactness when certain demands are made on the quality of thecolor pictures.

under pressure of a spring, is in direct contact with the shutter blade,respectively, with a part connected to it (the shutter blade). By thismeans, while outside the shutter opening, it is assigned to the shutterblade in such a manner that it follows its opening movement up to eithera fixed stop, or to a stop provided on the shutter blade itself in orderto be moved back immediately thereafter into the position outside of theshutter opening, in opposition to the efiect of the spring which isattached 'to it by the shutter blade returning to the closed position.This means that opening as well as final closing of shutter aperture isthe task of the shutter blade as in the conventional cameras, which arethe type from which the design of the invention was started. However,promptly after the inception of the opening movement of the shutterblade, the cover blade .is in a position to sweep out the shutteraperture and thus in following; to cover it partially, and to cover itfully temporarily. The cover blade, consequently has the character andthe function of a cover leaf for temporary action.

How this is conceived in detail, and other advantages are derived fromthe specific design of the invention, is

shown in the drawing and also described below bytwo designs andapplication examples.

The drawings show:

FIG. 1 represents a view of the inside of a camera with a single bladeshutter (automatic-shutter) in the originalposition which it (theshutter) assumes before the release is actuated;

FIG. 2 shows the same arrangement as in l, in a motion phase during thecocking process of the shutter;

FIG. 3 is a partial description of the shutter system depicted in FIGS.1 and 2 with the shutter blade freeing the passage through theobjective, and with the cover blade following at lower speed;

FIG. 4 shows the shutter system in the position in which the passagethrough the objective is fully freed, whereby the shutter blade is heldby an electromagnetic-mechanical blocking device;

FIG. 5 details the shutter system after release by the locking device onthe way of returning to the closed position;

FIG. 6 shows a further design example of an automatic shutter of thetype shown in FIG. 1 through 5 wherein a cover blade with several lightslits is assigned to the shutter blade;

FIG. 7 is a free plane time diagram as it is furnished by a single bladeshutter with a holohedral cover blade;

FIG. 8 is a total plane time diagram corresponding to the free planediagram according to FIG. 7;

FIG. 9 is a free plane time diagram of a single blade shutter, the coverleaf of which is additionally provided with a slit;

FIG. 10 is the total plane time diagram that corresponds to the freeplane time diagram of FIG. 9;

FIG. 11 is a plane line" diagram of the single blade shutter fitted withthe additional cover blade;

I the exposure times valid for the individual FIG. 12 shows the outlineof an objective aperturewith plane lines drawn in:

' FIG. 13 is a diagram evidencing that the relation of lines of theshutter aperture is not less favorable than is the case withconventional shutters;

FIG. 14 shows a single blade shutter equipped with mechanical means fortime control and with an additional cover blade;

FIG. 15 illustrates another design possibility of a single blade shutterwith a shutter blade that is movable back and forth in a straight lineand with an additional full plane cover blade, in which the openposition of the shutter blade system is indicated by dotted lines;

FIG. 16 illustrates an additional example of a single blade shutter witha shutter blade that oscillates in a straight line and a cover bladeprovided with an additional illumination slit;

FIG. 17 is a front view of a camera with the setter that serves to setthe objective;

FIG. 18 is a partial view of a camera with the switch that closes theflash circuit when a flash cube is mounted; and

FIGS. Hand 20 show the cooperation of the cover blade with the flashcontact provided for the ignition of In the drawings 1 indicates thehousing of a photographic camera that is only schematically indicated.The camera is equipped with a single blade shutter which functionsaccording to the principle of an automatic shutter. To mount the movableparts of the shutter system, there is a plate 2, indicated by dottedline in FIGS. 1 and 2, which has an exposure opening 3. According to thedesign example shown in FIGS. 1 through the shutter blade 5 mounted inpivoting fashion on a fixed axle 4, and to this shutter blade 5 aclosing spring 6 is attached. A drive lever 7 of two-armdesign whichsits in pivoting fashion on pin 8 works with the shutter blade 5 in amanner which will be more closely described below.

Pin No. 8 is mounted on the cocking and release slide 9 that isconnected in movable fashion to the camera housing 1. By means of a tang2a bent from a founda tion plate 2, and by means of a further tang 7abent from an arm of a drive lever 7, there is created a simple positiveguidance for this lever, a guidance which imparts to it, relative to thedrawing in FIGS. 1 and 2, a counter-clockwise torque when the cockingand release slide 9 is depressed. This torque momentum is absorbed by adrive spring which rests on one end of the drive lever 7 and on theother end of the cocking and release slide 9. The drive spring 10 storesthe cocking force. Since upon cocking and release of thecamera-release-mechanism 9, the drive lever 7, which it carries, carriesout a translating movement, during which the finger-like end 7b of thelever 7 that faces the shutter blade 5, assumes a course of movementindicated by a dotted line in FIG. I. This part eventually comes to'restbefore tang 5a that is formed on shutter blade 5. This means that afterthe disengagement of the drive lever 7 (FIG. 3) this lever drives theshutter blade 5 in opposition to the effect of the closing spring 6 withwhich it is connected and thus it moves the blade, tuming it around thefixed bearing pin 4 whereby the exposure aperture 3 is uncovered.

4 As the drawings in FIG. 1 through 5 also show, a cover blade 12 isassigned to the shutter blade 5 for the purpose of immediate andsuccessively intensifying covering of the freed exposure aperture 3.This blade 12 is placed upon a pin 13 in pivoting fashion and can bedriven by a spring 14. Pin 13 is mounted on foundation plate 2. 0n thecover blade 12 a tang 12a is formed, by means of which the blade, whichis under the influence of spring 14, is supported by the shutter blade 5proper. The assignment and positioning of the cover blade12, relative tothe shutter blade 5 is, in this case, so arranged, that, in the eventofthe opening movement of the opening and closing system, both bladesexecute turning movements in 1 opposite directions around theirrespective pivot pins 4 and 13 (FIG. 3). Furthermore it is conditionalon perfect exposure, that the cover blade 12 follows the opening move ofthe shutterblade 5 with lower acceleration and less run-off speed, whichcan be achieved in a simple manner; for example by weaker tension ofspring 14 relative to spring 10 which works on drive lever 7. In thesame way, the strength of the closing'spring 6, which works on shutterblade 5, is also weaker in relation to the force of spring 10.

.While, for setting the shutter blade 5 in its original position, a stop15 is provided, preferably made of elastic material,'for instance, ofrubber, a stop 16, serv ing tolimit the swing out range of the blade,can be made of hard material. Concerning the drive of the movableshutter parts especially, the force of springs 13 as indicated above canbe used. However, this does not exclude the use of a magnet force toopen and close shutter blade 5. This type of drive can be advantageouswhen electronically functioning switching is being used to control time.On the other hand, for the cover blade 12 a spring-powered drive isprovided exclusively for reason of favorable cost.

FIGS. 1 to 5 show in principle how the aforementioned controlarrangement serving to set the time, has to be made in detail, and howit can work together with above described shutter design, regardless ofwhich type of force eflects the opening movement of the shutter blade 5.One switch in these drawings is designated as 8,; it is located in themoving range of the switch pin 18 mounted on the cocking and releaseslide 9. In the contact position, achievable by the switch S,

which is brought about by the beginning of the movement of the cockingand release slide 9, the circuit of a generally known electronictiniesetting device 19, which is merely schematically indicated, on to apower source that is not further illustrated. For the purpose of lightdependent control, the camera can be fitted with a light sensitiveelement, for instance a hoto-resistance 2d, the resistance value ofwhich determines the time interval during which the shutter blade 5, asshown in FIG. 4, is held in the open position by an electromagneticmechanical blocking device. This device encompasses principally anelectromagnet 21, an anchor 22,

which works with it (the electro-magnet) as well as an anchor lever 23that carries the anchor. The anchor lever rests on a fixed pin 24 inpivoting fashion. A retracting spring 25 in contact with anchor lever 23holds it (the lever) in a final position determined by pin 26 (FIG. ll).Anchor lever 23 is furthermore provided with an additionalself-springing arm 23a which is assigned in such a fashion to the drivelever 7 respectively to a setting pin 28 mounted on the lever, that whenpressing down the cocking and release slide 9, the anchor 22 is forcibly(automatically) brought in contact before drive lever 7 slips off tang2a on the electromagnet 21. A hold-pawl 29, supported in spring fashionwhich a bent part of the holding pawl 29 snaps in, as

soon as, according to FIG. 4, the shutter reached the open position. 5

The designation S denotes a charge starting switch that is known and islocated'in the circuit of .the electronic time setting device 19. In theoriginal position of blade 5 has I the shutter blade 5, this switch isin contact owing to a pin 30 which is mounted on the shutter blade 5itself and influences its contact spring K, by which (in turn) a shortcircuit is created in the condenser of the time setting device. When theshutter blade 5 opens, the contact spring K follows the contact pin 30and opens the switch, thereby starting the time setting process.Immediately after the opening of the short circuit contact, the contactspring K comes to rest upon another contact assigned to it, a contactwhich is a parallel-contact to the switch S which has the task ofkeeping the battery circuit closed, even in the event that the cockingand release slide 9, under the influence of the retracting spring 31, isrelieved before the end of the time setting process. The above describedcamera design with single blade shutter and (an) additional cover bladeworks as follows: When, for the purpose of taking a picture, ,thecocking and release slide 9 is pressed down in the direction of thearrow in FIG. I, tip 7b of the drive lever 7 moves along the line ofmovement indicated by dashdots in FIG. 1. Tip 71; precedes in front ofthe tang 5a of the shutter blade 5. Anchor 22 is forced into contactwith the magnet2l by pin28 which is dependent on and moves synchronouswith the cocking movement of the slide. When finally, in the course ofthe cocking and release movement, tang 7a of the drive lever 7, comesout of touch with the positive guide 2a, then the drive lever 7,responding to the relatively strong spring 10 with which it is incontact, carries out a clockwise [rotary] motion around the bearing pin18. When this happens, the shutter blade 5 is taken along; the shutterblade 5 turns counterclockwise at high angular velocity around itsbearing pin and thereby opens the exposure aperture 3. Moved by a lesseraccelerating force, cover blade 12 follows the preceding shutter blade5, and by this motion it covers again the previously free exposureaperture 3. For further coordination of the cover blade 12 with theshutter blade 5 in connection with the closing of the shutter aperture,two events, differing one from the other in principle, can occur:

1. If the cover blade 12 has not freed fully the exposure aperture 3when passing over at the time when the shutter blade 5 moves back in theclosing direction after sliding off the tang edge 7b then the shutterblade, so to speak, takes along the cover blade on the way to closing.

2. If, however, the cover blade 12 as well as the shutter blade 5 fullyfrees the exposure aperture 3 before the shutter blade starts to movefor the closing, then the shutter blade is thereby fully slipped under,which means that the cover blade is taken along by the shutter bladepromptly at the outset of the closing.

' It is, however, characteristic in both cases that the cover blade 12has no functional significance when the exposure aperture isbeingclosed, as the closing of the exposure aperture 3 is exclusively thetask. of the shutter blade 5. The closing process is being initiatedalways after release of the anchor 22 respectively of the anchor lever23 by the electro-magnet 21 as a result of the through-switching of theelectronic time setting device. When this happens, then anchor lever 23which I as shown in FIG. 5 carries the holding-latch 29, lifts theblocking of shutter blade 5 that is held in the openposition, whereuponthe shutter blade, driven by the-closing spring 6, changes over into theclosed position, while taking along at the same time the cover blade 12.The moving path coveredby tang 7a of the drive lever 7 when a picture istaken is indicated in FIG. 2 by a dash-dotted line which also shows thatthe drive lever can reach the original position shown in FIG. 1 afterreturn by the cocking and release lever 9 merely by a littlecounter-clockwise turn around pin 8. To achieve this, the drive lever 7can, for instance, be coupled to the film transport device of the camera(which is not illustrated), in such a manner, that when the film ismoved the drive lever is moved also and is guided into the readyposition shown in FIG. 1.

A further design example is shown in FIG. 6. In structure and functionit very largely corresponds to the arrangement according to FIGS. 1through 5. For this reason the identical components have received thesame reference symbols.

To achieve the desired effect, a cover blade 30 with one or more slots30a of difierent or equal dimensions, was assigned to the shutter blade5 which moves back and forth during the exposure process. Fitting thecover blade 30 with additional slots 30a serves to achieve a specifiedexposure characteristic; an exact gradation of exposure time. This isimportant, particularly for cameras with electronic exposure timesetting where exposure times are supposed to be proportional to theresistance value of the photoresistance and thereby to the lightintensity. It must therefore be assured, for instance, that when a lightintensity reduced by one half prevails [relative to a specific lightintensity] a doubling of the exposure time takes place. Providingadditional light slots 30a in the cover blade 39 is advantageous tofulfilling this requirement. Such a desigi guarantees not only a minimalvalue for the shortest effective time, but also a good exposure timegradation in a camera with photo-resistance control. This is illustratedin a comparison of the two free-plane" time diagrams illustrated inFIGS. 7 and 9 of which the first reflects the curves developed in adesign of a full-plane cover blade, and the second the curves developedby the use of a slotted cover blade. A dash-dotted line A has been drawninto both diagrams. This line indicates the closing of edge A after anexposure time twice as a setting device has finished after a total of1.8ms

1.8ms 3.6ms following the starting signal. In the diagram according toFIG. 9, in which the shortest effective time is 2.4ms, the line A is,displaced in an analogous manner .by 2.4ms relative to the line A to theright on the time axis.

FIGS. 8 and 10 illustrate. the total planes resulting from considerationof line A and the shape of the curve relating to the line A isillustrated by a dash dotted line. For the example accordingto FIG. 7,the

result is that, instead of a theoretical time of 3.6ms an actual time of2.6ms is available which corresponds to a difference of about minus 28percent from the theoretical time. The difference, on the other hand,between actual time and theoretical time occurring as shown in FIG. 9 ismuch smaller. Instead of a theoretical time of 4. 8ms the actual time isabout 4.3ms which equals a difference of only about minus 11 percentrelative to the theoretical time.

For the next time interval also, which leads, in the example accordingto FIG. 7, to a theoretical time of 7.2 ms and in the example accordingto FIG. 9 to a theoretical time of 9.6ms, there are differences to theminus side of about equal size, while with the following time intervalsthe deviations become increasingly smaller. From this can be seen thatthe slot design used in the example according to FIG. 9 contributes to amuch smaller divergence from the actual time to the theoretical time atthe time gradation adjacent (following) the'shortest actual time. Itshould be mentioned in uniform width throughout their length; they mayfeature changing slot width for instance a wedge shape. This opens afurther possibility for fine adjustment in the sense of an equalgradation of the longer exposure times adjacent to the shortest actualtime.

To sum up, it thus demonstrated that by assigning a slotted cover bladeto the actual shutter blade it is not only possible to achieve asignificant shortening of the shortest effective time compared to thatof a traditional shutter design, but that in addition, also withautomatic exposure time setting, as known from shutters with electronictime control and photo-resistance control, a sufficiently accurategradation of the exposure times connected to the shortest effective timeis assured in relation to the theoretical characteristic.

As previously already indicated, the assignment of a cover blade to anoscillating shutter blade for cameras with exposure time setting of anykind is of importance, even for cameras with time control by means ofrun off of a mechanical retarding mechanism that slows down orinterrupts the shutter blade system, respectively with a reflex stopeffecting limitation of the deflection range upon opening and closing aswell as its (the shutter blade system's) return.- In lieu of other formsof shutter designs with mechanical time control, FIG. 14 shows one bywhich the deflection range of shutter blade 5 is more or less. limitedthrough an adjustable reflex stop 32 carrying graduations 32a. If thetime setting member, as shown, is set for instance to 1/30 sec, the

gradation 32a, positioned closest to the axis 33 of the reflex stop 32,becomes effective, whereby the shutter blade. registers the largestdeflection. Contrarily the shutter blade comes in contact with thegradation 32a after only a short deflection range; gradation 32a isfurthest away from pivot 33 of the reflex stop 32. This happens when themarker 34 of the merely schematically indicated time setting member 35has been set to the time value 'l/500 sec of the scale 36. But thesituation is always that the additionalcover blade 12 or 30 follows theactual shutter blade 5 beginning with the opening movement.

In FIG. 11 a plane-line-diagram is shown, which.

. been stroked over (swept clear), a 100 percent free plane has beenachieved. When fewer strips are stroked over (swept clear) acorrespondingly lower percentage is achieved, as FIG. 1 1 shows.

FIG. 15 contains a schematic sketch of a slide shutter, wherein a coverblade 41 also formed from a slide is assigned to a straightlinear-guided, back and forth moving slide 39. This slide effectsboth-the opening and the closing of the exposure opening 38. A coverblade 41, also formed from a slide and under the influence of a spring40 is also assigned to slide 39. Directionally opposed arrows in thedrawing indicate the drive and closing forces for the opening andclosing slide 39, while the element serving to transmit the driveforces, which may, for instance, be designed as a lever,

. is designated as 42. The lever and the slide 39 may be coupled withone another in form-locking fashion with the aid of a pin-slotconnection, whereas the cover blade 41 is positively (or inforce-locking manner) connected to the lever by means of an arm 41awhich is under the influence of spring 40. A designates that edge of theopening or closing slide 39 which determines the exposure whereas theedges of the cover blade 41 are designated as B and C. While FIG. 15refers to a slide shutter with a full surface cover blade, FIG. 16illustrates another design example of a slide shutter in which a coverblade 44 fitted with a slot 44a is assigned to the back and forth movingslide shutter 43.

' Area-Strips.

ing time is about 2ms and the closing time about 3ms.'

This can be seen in he illustrations according to' FIGS. 7 and 9 bythe'fact that lineA passes-2ms and line A passes 3ms, and that adistance of Sms exists between the point on line A at which 50 percentof the opening area is freed,and the point on line A at which50 per centof the opening area is closed.

In the plane diagrams according to FIGS. 7 and 9 the vention. Theselight intensity differences result from the principle of functioning inthe case of single blade shutters behind the lenses.

To take flash bulb photographs it is fundamentally necessary that theflash contact takes place timewise definitely dependent on the freeingof the shutter open- I ing. In further development ofthe aforementioneddesign of a single blade shutter with additional cover blade, it isadvantageous when taking flash bulb photoopening characteristic of edgeAof the shutter blade is designated as A and the closing characteristicof. the same edge is designated as A The diagram lines formed by theedges B and C (FIG. 15) and the edges a,b,c and d (FIG. 16) arefurthermore, designated as B and C respectively as a,b,c and d.

The drawings according to FIGS. 7 and 9 are called Free-Area-Time-Diagrams. This means that from each sketch the Free Area resultingfrom each position of shutter blade and cover blade are visible. Thetemporary covering of the exposure aperture caused by the cover blade ismarked by one (full area cover blade) respectively two (slotted coverblade) shaded or lined The time diagrams according to FIGS. 8 and 10,which are called Total Surface-Time-Diagrarns, show a plotting ofdiagrams according to FIGS. 7 and 9 and reveal the percent of theexposure aperture which is freed by the shutter blade at every movementof the sweep. The zero point of the time scale is the beginning of thefreeing movement of the exposure aperture by the shutter blade. Thesurface under the curves is thus a measure for the light passage throughthe shutter aperture ije. for a definite quantity of light. To measurethe progressivity of the combination design of a single blade shutterwith a cover blade versus the traditional arrangement, the surface underthe curves in FIGS. 8 and 10 should be compared with the surface underthe curve path A, 100 percent line, A, in FIGS. 7 and 9. In the exampleaccording to FIG. 7 of an effective exposure time of 5ms=1/200 sec ofthe traditional design, this results in an effective time ofl.8ms=approx.l/550 sec for the camera described and illustrated while inthe case of the example according to FIG. 9 the efiective time achievedis about 2.4ms-about 1/420 sec. It is thus evident that by means of asingle blade shutter to which a cover blade is additionally assigned, ashorter efi'ective time can be achieved considerably less than half ofthe previous time while keeping the opening and closing drive forces ofa traditional shutter. In all design variations the point of departureis a constant value of the effective shutter aperture.

In FIG. 13 it is shown that the relation of the valid exposure times ofthe above described type of shutter is not less favorable for theindividual lines of the shutter aperture than is the case with shuttersof traditional design. This means that the quality with reference tolight intensity differences, characteristic and accepted in the knowncameras, are assured in equal measure in cameras designed according tothe ingraphs, that the flash contact switch 8,, according to- FIGS. 19and 20 is actuated depending on the movement of the cover blade 12 inorder to set the time for the flash bulb photo in such a manner that theshutter blade 5 and the cover blade 12 free the entire exposure aperturesimultaneously, at least for a short time. To accomplish this result thefocusing device is moved from the position heretofore defined to a flashoperating position. If this prerequisite is met, then flash photos canbe made with flash bulbs as well as with electronic flashes. However, inthe case of electronic flashes it is necessary that contact be givenonly when the' cover blade 12 also has freed fully the exposure aperturewhereas when photographing with flash bulbs, contact can already be madeat an earlier instant, for example, at the beginning of the movement ofcover blade 12. While in FIG. 17 the use of the single blade shutterwith additional cover blade is shown on a camera with objective settingFIG. 18 shows the design of a contact switch 8,, which, in knownfashion, switches the photo-resistance off the electronic time settingcontrol, depending on the mounting of a flash cube 46 onto the camera(position Blitz), and in lieu of the photo-resistance switches on aconstant resistance, which results in a time suitable for flash bulbpictures, for example, l/3O sec.

What is claimed is:

1. A photographic camera having an objective lens operating with aconstant diaphragm aperture;

a shutter having a single main shutter blade reciprocated by an openingand closing drive means across a shutter opening;

a cover blade associated with said main shutter blade moving in a planeparallel to the plane of movement thereof;

said cover blade being designed to sweep over the aperture and beingspring biased against said main shutter blade such that the said coverblade follows the main shutter during the opening movement of the latterto a stop provided on said main shutter;

said cover blade being subsequently moved by said main shutter blade onits return to a closed positron;

said cover blade returning to a position displaced from the apertureagainst the action of said spring biasing means.

2. A camera according to claim 1, wherein said main shutter blade andsaid cover blade execute opposite directions of rotation about theiraxes during rnovement.

v3. A camera according to claim 1 wherein said cover blade isconstructed as a lever-like cover with an unbroken surface.

4. A camera according to claim 1 wherein the force of the biasing springacting on said cover blade is less than the drive force producing theopening and closing movement of the main shutter blade.

8. A camera according to claim 1 which includes a l flash contactfocussing and a focusing device, said focussing device also acting as anexposure time setter and comprising a flash" operating position, whereinan exposure time is set in the flash operating position during which theshutter blade and the cover blade simultaneously expose the full shutteropening at least briefly, and wherein the flash contact is actuable bymovement of said cover blade.

1. A photographic camera having an objective lens operating with aconstant diaphragm aperture; a shutter having a single main shutterblade reciprocated by an opening and closing drive means across ashutter opening; a cover blade associated with said main shutter blademoving in a plane parallel to the plane of movement thereof; said coverblade being designed to sweep over the aperture and being spring biasedagainst said main shutter blade such that the said cover blade followsthe main shutter during the opening movement of the latter to a stopprovided on said main shutter; said cover blade being subsequently movedby said main shutter blade on its return to a closed position; saidcover blade returning to a position displaced from the aperture againstthe action of said spring biasing means.
 2. A camera according to claim1, wherein said main shutter blade and said cover blade execute oppositedirections of rotation about their axes during movement.
 3. A cameraaccording to claim 1 wherein said cover blade is constructed as alever-like cover with an unbroken surface.
 4. A camera according toclaim 1 wherein the force of the biasing spring acting on said coverblade is less than the drive force producing the opening and closingmovement of the main shutter blade.
 5. A camera according to claim 1wherein said cover blade Is a rotatable segment-like disc provided withone or more slits extending radially relatively to its center ofrotation.
 6. A camera according to claim 5, wherein said slits are ofdiffering widths.
 7. A camera according to claim 5, wherein said slitsare wedge shaped.
 8. A camera according to claim 1 which includes aflash contact focussing and a focusing device, said focussing devicealso acting as an exposure time setter and comprising a ''''flash''''operating position, wherein an exposure time is set in the ''''flash''''operating position during which the shutter blade and the cover bladesimultaneously expose the full shutter opening at least briefly, andwherein the flash contact is actuable by movement of said cover blade.